Mercapto azoles in developer for mixed grain photographic process



Oct- 1952 'B. H. CARROLL ETAL ,61

MERCAPTO AZOLES IN DEVELOPER F0 MIXED GRAIN PHOTOGRAPHIC PROCESS Filed D90. 20, 1949 DEVELOPED IN MQ DEVELOPER CONTAIN/N6 A MERCAPTO AZOLE RES/DUAL S/L VER HAL/DC GRAINS SELECT! VELY EXPOSED, COLOR'DEVELOPED AND FIXED BURT H.- CARROLL FORREST A. RIEHEY xIylfiTVENTORS Q MMM ATTORNEYJ Patented a. 21, 1952 UNITED STATES PATENT 1 OFFICE MERCAPTO AZOLES IN DEVELOPER FOR MIXED GRAIN PHOTOGRAPHIC PROCESS Burt H. Carroll and Forrest A. Rickey, Rochester, N-. Y., assignors to Eastman Kodak Company, RochestenN. Y., a corporation of New Jersey Application December 20, 1949, Serial-No. 134,044

This invention relates to color photography and particularly to a mixed grain photographic process. In mixed grain processes, a mixture of sensitive silver halide grain sensitized to record different regions of the spectrum is used and a layer sensitized in this way may be combined on a single support with a layer sensitized to record only a single spectral region.

One of the defects encountered in color processes in which two or more of the component images are recorded in a single film is the occurrence of inter-image effects. By inter-image effects, we mean that the density of one of the component images is controlled not only by the exposure and development of the appropriate emulsion grains, but also by the development of other component images in adjacent layers or in adjacent areas of the same layer. These effects 'may be present in layer processes as well as in mixed grain processes. In mixed grain processes, for example those in which there is a negative development followed by selective exposure of the residual silver halide grains and color development of these grains to produce a reversal image, physical development may produce one of the more serious of these inter-image efiects. Physical development brings about the exhaustion'of the unexposed grains in the vicinity of exposed grains with consequent loss of density.

For example, in a mixed grain coating processed *by selective re-exposure to produce reversal images, an area exposed to red light" only will produce developable red-sensitive. grains in proportion to the exposure, while green-sensitive and blue-sensitive grains should not be affected. The

first development, for example, in an M-Q developer (a developer in which monomethyl-pamino phenol and hydroquinone are the principal developing agents), would be followed by exposure to red. light and development in a cyan coupler developer, exposure to green light and development in a magenta coupler developer and finally exposure toblue or white light and development in a yellow coupler developer. In the area exposedto red light, red-sensitive grains should become developable in the M-Q developer While the others should develop only in the ap propriate coupler developers, giving anarea of full strength of magenta and yellow and Without cyan dye if therewas full red light exposure in .1 thatflarea. If, however, there is physical development in the M-Q developer, some of the green-sensitive and blue-sensitive grains willbe dissolved and deposited on the silver deposited from the red-sensitive grains and the magenta 5 Claims. (Cl. 952) and yellow dyes will not have full intensity in the final image. Corresponding errors would be produced by physical development in the first or second color developers. A. marked degree of physical development might be objectionable in any type of reversal processes including" black and White, and innegat ive processes, either black and white or color, it "introduces. distortions of the reproduction scale which may be objectiona-ble.

It is therefore an object of the present invention to provide a methodfor controlling interimage efiects in a mixed grain photographic layer. A further object is to provide a method for decreasing color degradation in a mixed grain emulsion layer. A still further. object is to pro- O as 2 mercapto-benzoxazole 2-mercapto-benzothiazole The accompanying drawing illustrates in; sectional views a mixed grain film at successive stages in our process. 1

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According to our invention, a -mixed grain photographic coating is used which may have three differently sensitized silver halide particles coated as a single layer as described, .for example, in Mannes and Godowsky U. S. Patent 2,338,856, or the red-sensitive and green-sensitive silver halide grains may be incorporated in a single layer, with the blue-sensitive silver halide grains in a separate layer, either containing a yellow filter dye or separated from the mixed grain layer by an inter-layer containing" a yellow coloring material. After exposure of the mixed grain element, it is developed in a black-andwhite developer, preferably an lVi-Q developer, containing one of the mercapto azoles referred to above. This produces negative silver images in the region of the emulsion layer or layers which were exposed to blue, green or red light. Colored images:arethenproduced in the layer by selective re-exposure-and color development. For example, the element is exposed to red light and developed in a developing solution containing'a primary aromatic amino coloring developing agent and a cyan coupler, that i=is,":a .ooupler capable of producing a cyan image upon-development. The residual. green-sensitive. "silver halide grains are next exposed; with; green light and the element developed in: a. color developer containing a magenta coupler. The only remain-- ing sensitive grains are the blue sensitive grains; and the element may therefore be exposed to either blue light or White light followed by developmentinua coupler developer. containing. a

yellow-forming coupler. .After conversion voflthe .developed silver to a silver salt..and=fixing,..the element contains. colored. images corresponding .to ,.the original subject. photographed.

' The following example illustrates a film processed according to. our invention.

A mixed grain emulsionwas' made by sensitizing a silver chlorobromide emulsion to red light with an 8-alkyl or 8-phenyl-3,4,3,4-dibenzothiocarbocyanine dye .as described .inmBrooker UL. SI Patent/$11,969,444 and 1,969,447, andmixing itwith anequal... quantity .of a silver bromide .-emulsion sensitized to green light. with a 3,4- .benzothiae2fl-cyanine.dye. as described in Brooker U'. 5.. Patent. 1,935,696. r This emulsion was coated Y on a suitablysubbed .celluloseorganic acid ester Lfilmjsupport andwhendry, was coated-withian .unsensitized. silver bromide. emulsion containing .tartra'zineasafilterdye to limit theactionoof blue light to the unsensitized emulsion.

..The film prior-to exposure is illustratedin the first stage of the accompanying drawing'where I is the film support coated withemulsion layer H of mixed green-sensitive and red-sensitive emulsions and. the. blue-sensitive emulsion layer .12 containing a yellow dye.

The film prepared in this way-was exposed "duced by'green exposure and [3 indicates the negative silver produced by red exposure. The negative silver images I! and I8 are shown as being lessdense than the'negative image [6; this is merelyby-wayof illustration to indicatelthat .inithe" portion ofilayer H exposed to. green light there are unexposed andundeve'loped red-sensi- ..tive,,grains andinthe portion of layer I Lexposed '4 red light there are unexposed and undeveloped green-sensitive grains.

After washing the film for about minutes, it was exposed through the base for about 20 sec- 5 onds to 100-foot candles of light through a red filter transmitting light of longer wave length a. than 640 millimicrons, to: expose the residual "red-sensitive: grains and was then developed for 12 minutes in a color-forming developer which may have the following composition:

. A. Grams p-Amino'di'ethyl aniline HCl 2 Sodium. su1fite r... 6

Sodium carbonate 50 =Pota'ssium bromide 5 Potassium thioc yanate 1 Water to 950420.

B. Grams o-I-Iydroxy diphenyl 3 Sodium .hydroxide L eshrew-silica 5 Water.

(For use; Solution B is added'to Solution .The film was then exposed 'fromthesuppo'rt side to green light of an intensity of from 2,000 to 13,000-foot' candles for about'20 seconds to expose the residual green-sensitivegrainsand the film was then developed'for about 10 minutes in a developer which may havethefollowingcomposition:

(For use, Solution 1B is added-to SolutionlA.)

.The film wasthen-exposed for about'20 seconds to approximately 2,000-foot candles of white light to expose the residualblue-sensitive silver halide grains anddevelopedfor about. five minutes in a developer which may have the following. composition to an object or image represented in the draw- A. 'lGrams ing by a'filter having a blue portion l3, a green 51) portion land a red portion Hi. This .exposure ggg g giggg amlme """'""'.i is followed by, negative development for 10 I um 6";:" 1 minutes at 20C. in a developerwhich may have w .95 the following composition: Grams 55 Grams N-methyl p-aminophenol sulfate 6 Aceto'acet anilifle [j10 Hydroquinone l 10 Sodiumflhydroxideo i 1 Sodium sulfite c 50 Water 10 00.,

Sodium carbonate 30 L .(For use, solutlonB is added to So1ut1on.:A.) i i 3' After development in the yellow 'color forim- P any ,mercapto e razo e ing developer, the film was washed for aboutzfive Water to 1 hter' minutes; and bleached for ab'out 'six -minutes in The film afte negative development .isshown a solution having the'following composition: :in the :second stage I of thedraw Where Potassium ferricyanideufi grams .50 indicates the negative silver producedby the-blue Ammonium hydroxide (28%. solutionlmecg 2. --exposure, l'l'indicates the negative silver'pro- Potassium bromide c figramsu J15 Water to 1 liter.

The film was then fixed for about five minutes in h yo; washed" for several .minutes and dried in warm. air. It thenfappeared as 'shown' in the .final stage of the drawing in which, l9 :indicates theyellow image in layer l2, 20indicates-=.the magneta image in layer 1 Land-2| indicates the cyan imageinlayerl l.

The photographic efiects of the mercapto azoles used according to our invention are illustrated by the following data obtained with a two-layer coating of the type described in the specific example.

The film was developed in the M-Q developer described above and a control experiment was developed in the same developer without the 1- phenyl-fi-mercapto tetrazole. The emulsion, after first development in the M-Q developer, was successively flashed with red light, developed in a cyan coupler developer, flashed with green light, developed in a magenta coupler developer, bleached, fixed, washed and dried as described in the specific example. The equivalent neutral densities were measured in a color densitometer (see Evans, Journal Society Motion Picture Engineers, 31, 194, 1938) for a definition of equivalent neutral density and a description of the densitometer in a neutral area and the green area with results shown in the following table.

Equivalent neutral densities In the neutral area, both green-sensitive and red-sensitive grains were developed so that there was no selective physical development of one on the other and the cyan and magenta images were the same in both developers; there was, however, a loss of yellow density in the control which was corrected by the presence of the 5- phenyl-l-mercapto tetrazole. In the green area (made up of cyan and yellow dyes) green-sensitive grains were made developable in large numbers, and in the control development there was considerable physical development of red-sensitive grains onto the green-sensitive grains with loss of cyan density. This along with the yellow was corrected by the mercapto tetrazole as shown by the table.

It will be understood that the modifications, for example, included here areillustrative only, and that our invention is to beitaken as limited only by the scope of the appended claims.

We claim:

1. The method of controlling the inter-image effects in the development of a silver halide emulsion layer containing at least two sets of silver halide grains, each set being sensitive to a different spectral region, which comprises exposing said layer to a colored object or image and developing it in a black-and-white developer containing an azole having a mercapto substituent, and then successively exposing the sets of residual silver halide grains to light to which each set is sensitive and successively developing said sets of silver halide grains to different colored images in said layer with different color forming developer solutions.

2. The method of controlling the inter-image effects in the development of a silver halide emulsion layer containing at least two sets of silver halide grains, each set being sensitive to 5 adifferent spectral region, which comprises exposing said layer to a colored object or image and developing it in a black-and-white developer containing 1-phenyl-S-mercaptotetrazole, and then successively exposing the sets of residual silver halide grains to light to which each set is sensitive and successively developing said sets of silver halide grains to different colored images in said layer with different color-forming developer solutions.

3. The method of controlling the inter-image effects in the development of a silver halide emulsion layer containing at least two sets of silver halide grains, each set being sensitive to a different spectral region, which comprises exposing oping it in a black-and-white developer containing l-phenyl-2-mercaptothiazole and then successively exposing the sets of residual silver halide grains to light to which each set is sensitive and successively developing said sets of silver halide grains to different colored images in said layer with different color-forming developer solutions.

4. The method of decreasing color degradation in a mixed grain photographic layer containing silver halide grains separately sensitive to the red and green spectral regions, which comprises exposing only a portion of the silver halide grains of said layer to a colored object or image and developing them in a black-and-white developer containing an azole having a mercapto substituent and then successively exposing residual red-sensitive grains of said layer to red light and developing them in a color developer, and exposing residual green-sensitive grains of said layer and developing them in a different color developer.

5. The method of decreasing color degradation in a mixed grain photographic layer containing silver halide grains separately sensitive to the red and green spectral regions, which comprises exposing only a portion of the silver halide grains of said layer to a colored object or image and dew ing' them in a different color developer.

BURT H. CARROLL. FORREST A. RICHEY.

REFERENCES CITED UNITED STATES PATENTS Name Date Kendall July 16, 1946 Number said layer to a colored object or image and develgr'enPsensitive grains of said layer and develop- 

1. THE METHOD OF CONTROLLING THE INTER-IMAGE EFFECTS IN THE DEVELOPMENT OF A SILVER HALIDE EMULSION LAYER CONTAINING AT LEAST TWO SETS OF SILVER HALIDE GRAINS, EACH SET BEING SENSITIVE TO A DIFFERENT SPECTRAL REGION, WHICH COMPRISES EXPOSING SAID LAYER TO A COLORED OBJECT OR IMAGE AND DEVELOPING IT IN A BLACK-AND-WHITE DEVELOPER CONTAINING AN AZOLE HAVING A MERCAPTO SUBSTITUENT, AND THEN SUCSESSIVELY EXPOSING THE SETS OF RESIDUAL SILVER HALIDE GRAINS TO LIGHT TO WHICH EACH SET IS SENSITIVE AND SUCCESSIVELY DEVELOPING SAID SETS OF SILVER HALIDE GRAINS TO DIFFERENT COLORED IMAGES IN SAID LAYER WITH DIFFERENT COLORFORMING DEVELOPER SOLUTIONS. 